Historical research on refraction in the modern era has often focused on the question of attributing the law of refraction to Descartes, Snel and Harriott. The discovery of Ibn Sahl’s work has put an end to the dispute over priority between these authors, leaving another problem largely unnoticed: most of the literature refers to this discovery without distinguishing the native form of the statements on refraction from the current conception of the law of refraction. This anachronism is problematic. Ancient texts do not contain a single statement of the law of refraction as we know it today. Descartes’ contribution is in line with Maurolico’s and Kepler’s work on refraction. Like them, Descartes makes no mention of sines or refractive indices, nor does he formulate a physical law of refraction. Since these ideas developed gradually between the late 17th century and the 19th century, the recognition of a “law of sines” or a “law of refraction” is not an idea native to the 16th and 17th centuries. We suggest that the work of Descartes does not fit into the modern quest for the laws of nature, but rather into the framework of the theory of proportions.

Contrary to the standard account that credits Francesco Maria Grimaldi (1618–1663) with the discovery of diffraction, we show that this optical phenomenon had been described nearly a century earlier in Problemata ad perspectivam et iridem pertinentia by Francesco Maurolico (1494–1575). This text probably served as a source for Grimaldi’s Physico-mathesis de lumine, in which Maurolico’s observation is reported almost verbatim. We must therefore backdate the discovery of diffraction to 1567 and reassign the roles. We translate the passage, reconstruct the result, and draw the consequences of this discovery.

In 19th century editions, Gaspard Monge's Trait & eacute; des ombres is given as an application or complement to Descriptive Geometry. This presentation is anachronistic: the first handwritten copy of the treatise is dated 1766; Descriptive Geometry was taught at the & Eacute;cole Polytechnique and the & Eacute;cole Normale from 1795, and published in 1799. The treatise therefore predates Descriptive Geometry by thirty years. This is a critical edition of the Trait & eacute; des ombres based on handwritten copies made by Monge's students at the & Eacute;cole royale du g & eacute;nie de M & eacute;zi & egrave;res. The critical edition aims to restore the text to its original form. A linear concepts of optics and perspective, obscured by the application of Descriptive Geometry. commentary explains the passages referring to the

Abstract. The EPICA (European Project for Ice Coring in Antarctica) Dome C (EDC) ice core drilling in East Antarctica reaches a depth of 3260 m. The reference EDC chronology (AICC2012) provides an age vs depth relationship covering the last 800 kyr (thousands of years) with an absolute uncertainty rising up to 8,000 years at the bottom of the ice core. The origins of this relatively large uncertainty are threefold: (1) the δ18Oatm, δO2/N2 and total air content (TAC) records are poorly resolved and discontinuous over the last 800 kyr, (2) the three orbital tools are not used simultaneously and (3) large uncertainties are associated with their orbital targets. Here, we present new highly resolved δ18Oatm, δO2/N2 and δ15N measurements for EDC ice core covering the last five glacial – interglacial transitions as well as novel absolute 81Kr ages. We have compiled chronological and glaciological information including novel orbital age markers from new data on EDC ice core as well as accurate firn modeling estimates in a Bayesian dating tool to construct the new AICC2023 chronology. The average uncertainty of the ice chronology is reduced from 2,500 years to 1,800 years in AICC2023 over the last 800 kyr. The new timescale diverges from AICC2012 and suggests age shifts reaching 3,800 years towards older ages over Marine Isotopes Stages (MIS) 5, 11 and 19. But, the coherency between the new AICC2023 timescale and independent chronologies of other archives (Italian Lacustrine succession from Sulmona Basin, Dome Fuji ice core and northern Alpine speleothems) is improved by 1,000 to 2,000 years over these time intervals.

The EPICA (European Project for Ice Coring in Antarctica) Dome C (EDC) ice core drilling in East Antarctica reaches a depth of 3260 m. The reference EDC chronology, the AICC2012 (Antarctic Ice Core Chronology 2012), provides an age vs. depth relationship covering the last 800 kyr (thousands of years), with an absolute uncertainty rising up to 8000 years at the bottom of the ice core. The origins of this relatively large uncertainty are twofold: (1) the δ18Oatm, δO2/N2 and total air content (TAC) records are poorly resolved and show large gaps over the last 800 kyr, and (2) large uncertainties are associated with their orbital targets. Here, we present new highly resolved δ18Oatm, δO2/N2 and δ15N measurements for the EDC ice core covering the last five glacial–interglacial transitions; a new low-resolution TAC record over the period 440–800 ka BP (ka: 1000 years before 1950); and novel absolute 81Kr ages. We have compiled chronological and glaciological information including novel orbital age markers from new data on the EDC ice core as well as accurate firn modeling estimates in a Bayesian dating tool to construct the new AICC2023 chronology. For the first time, three orbital tools are used simultaneously. Hence, it is possible to observe that they are consistent with each other and with the other age markers over most of the last 800 kyr (70 %). This, in turn, gives us confidence in the new AICC2023 chronology. The average uncertainty in the ice chronology is reduced from 1700 to 900 years in AICC2023 over the last 800 kyr (1σ). The new timescale diverges from AICC2012 and suggests age shifts reaching 3800 years towards older ages over marine isotope stages (MISs) 5, 11 and 19. But the coherency between the new AICC2023 timescale and independent chronologies of other archives (Italian Lacustrine succession from Sulmona Basin, Dome Fuji ice core and northern Alpine speleothems) is improved by 1000 to 2000 years over these time intervals.

Optical instrumentation, as a modern technology, was born with the invention of the telescope and microscope and the geometrical theory of image formation. The development of optical instrumentation has been closely linked to ideas about the optical functioning of the human eye, including the old but questionable metaphysical idea that the eye is a perfect optical system. We analyse how this notion shaped the research paths followed by some of the most important contributors of optical instrumentation, from Kepler (1571-1630) to Helmholtz (1821-1894). It is shown that this idea influenced crucial aspects of scientific practice such as the definition of scientific purposes, ways of arguing and reasoning, and the establishment of new hypotheses. It even inspired the design and development of new optical instruments. During the 19th century, the presupposition of the eye as a perfect optical instrument lost popularity due to better knowledge of the anatomy of the human eye and its optical properties, and the growing influence of Darwin’s (1809-1882) theory of natural selection.

This article aims at identifying the sources of fols. 395r and 686r-686v of the Codex Atlanticus. These anonymous folios, inserted in Leonardo da Vinci's notebooks, do not deal with the duplication of the cube proper, nor do they derive from Giorgio Valla's De expetendis et fugiendis rebus (1501), as has been claimed. They deal specifically with the extraction of the cube root by geometric methods. The analysis of the sources by the tracer method reveals that these fragments are taken from the Practica geometrie by Leonardo Fibonacci (1220) and, more precisely, from a volgarizzamento that appears in the Praticha d'arismetrica by Benedetto da Firenze (1463). Leonardo could have consulted this text in one of his two Florentine periods, around 1463-1482 or around 1503-1506. (c) 2023 Published by Elsevier Inc.

Abstract. Seasonal temperature reconstructions from ice cores are missing over glacial-interglacial timescales, preventing a good understanding of the driving factors of Antarctic past climate changes. Here the total air content (TAC) record from an Antarctic ice core is analyzed over the last 440 thousand of years (ka). While the water isotopic record, tracer for annual mean surface temperature, exhibits a dominant ~100 ka cyclicity, the TAC record is associated with a dominant ~40 ka cyclicity. Our results show that the TAC record is highly correlated with the mean insolation over the local astronomical half-year summer. It also shows for the first time that it is highly correlated with local summer temperature simulated with an Earth system model of intermediate complexity. This suggests that the Antarctic TAC records could be used as a proxy for local summer temperature changes. Also, our simulations show that local summer insolation is the primary driver of Antarctic summer surface temperature variations while changes in atmospheric greenhouse gas concentrations and northern hemisphere ice sheet configurations play a more important role on Antarctic annual surface temperature changes.

3 δ 18 O atm δO 2 /N 2 TAC EDC depth (m) Gas age (ka BP) Uncertainty (years) Source EDC depth (m) Ice age (ka BP) Uncertainty (years) Source EDC depth (m) Ice age (ka BP) Uncertainty (years)